Maksutov cassegrain help

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gooseholla
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Maksutov cassegrain help

Post by gooseholla »

Hello.

I have been using an 8 inch Celestron Newtonian for 4 years now. However, I'm looking to get out and about so want a smaller telescope to go in my small car - and one that is lighter to carry, setup etc... Therefore, I am looking at a Maksutov Cassegrain. However, I know nothing of what to look for, or what is any good.

Not looking to spend huge amount on one, say c.£300. So what size should one look for? What are the benefits over a newt. etc?

Any help appreciated.
Last edited by gooseholla on Wed Oct 26, 2011 7:24 pm, edited 1 time in total.
David Frydman
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Post by David Frydman »

Welcome,
They are actually called Maksutov after the Russian designer Maksutov who invented them in 1940, although a Finnish designer Vaisalla, spelling ? may have thought of the idea earlier.
They are normally of longer focal ratios f//13 to f/15 to f/20 than Schmidt Cassegrain telescopes at f/10 commonly.
Ordinary Cassegrains are not common nowadays, although similar Dall Kirkhams are.

I would suggest a Skywatcher 127mm Maksutov which is around £300.
Look on OVL website. They only sell through dealers and the price varies.
I have one and Smerral, BRIAN who posts in gallery uses one with a webcam.

I am not computer literate so cannot advise on mounts or digital imaging, but hopefully someone else here can.

The 127mm tube and optics is light but on the OVL website you can see the total weight with mount.

I use mine visually on a heavy good photo tripod.
OVL also do a Horizon tripod at about £80 if you just want to use it visually and carry it easily in a car.

Regards, David
David Frydman
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Post by David Frydman »

There are no real benefits over a Newtonian although they are good on planets with the higher magnifications from the same eyepieces.
They are compact.
The field of view may be smaller as you cannot use very low magnification.
They are of a more complex design than a Newtonian,

You might also consider a 100mm or 120mm f/5 refractor also shown on OVL website.

David
brian livesey
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Post by brian livesey »

I have a CELESTRON 100mm/f.5 refractor, but the problem here is chromatism. This is very evident on moderate to high magnifications. A partial cure is to use a BAADER Semi-Apo filter.
It's difficult for a non-expert to say, but I reckon that the filter removes 60% or so of the chromatism. Are there any expert reviews on semi-apo filters?
brian
gooseholla
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Post by gooseholla »

Yes, I know they're called Maksutov, I don't know how it ended up as Makarov. '(although looking at the place of the keys on the keyboard may provide an answer).

I've got a photo tripod, that I use for binos. Presumably, though, i'd need some kind of weight hanging off the bottom with a telescope on it?
Not really looking to do any photography with it, initially. Just want something I can go out and about with or view a lot in a short time.

I was looking at the c. 4inch Skywatcher OTA. Around £165. The 127mm is about £100 more for the OTA. 55% more light gathering, but is it worth the extra £100?

I don't use very low mags anyway on my 8inch. I have a 3.6mm, but I rarely use it, as the conditions are never very good round here. I'm happy with 100 -150x. Like looking at deep sky objects, etc... My fav eyepiece range is 25mm to 15mm.

Thanks for all the replies so far.
Ender Of Days
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Post by Ender Of Days »

Ive had my ETX 125 for a while now and have (so far) not had an issue with it,
they come in around the £600 mark which may be a bit steep for you,
so the similar Skywatcher is nearer the mark,
not sure what tripod you get with the Skywatcher though,
If you could get a wider field short tube reflector (poss dob) that would be better as you will see fainter object's as the f15 of my 125 is not good for faint Galaxies,

Its a problem nearly everyone goes through,a small portable scope that can do everything from Galaxies to planets,whereas Im primarily a Galaxy bloke I went for my scope to shift me toward Lunar and Planetary observing something Id ignored before hand :)

Hope that helps,

JJ..
aint no speed limit where im comin from ..
lets hit the highway doing 69


ETX 125
Meade Series 4000 box set
gooseholla
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Post by gooseholla »

Money isn't necessarily going to be the problem. I could save more, if something exceptional was about.

I'm slowly saving for a larger newt, but obviously, that'll never leave the garden!

I'm not one of those who goes for everything. I look at the planets - not every night, not all the time, not in great detail. I'm interested, however, in seeing clusters of stars, galaxies, etc. However, light here isn't always great (houses, passing cars, street lights).

I'm torn between getting a Skywatcher OTA only or saving and getting a GO TO one. I know it makes viewing quicker, etc. But, just more things to worry about lugging out with me!
David Frydman
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Post by David Frydman »

The photo tripod would have to be good and weigh 2.5 to 3.5 kg to support the 127mm Mak or the 102mm f/5 refractor.

Sherwoods were selling Celestron 102mm f/5 optical tubes complete for £95 but may have sold out.

OVL have various short focus refractors including a substantial tripod as a terrestrial/astro package.

The 127mm has a central obstruction so the light gathering is less than an unobstructed 127mm.
However there is virtually no false colour with a Mak.

The original Maksutovs and Schmidts were fast photo cameras. You are correct that the full name is Maksutov/Cassegrain or Schmidt/Cassegrain.
There are faster Mak systems with a separate secondary usually at f/10.

It can only be a personal choice.

I like the very lightweight Yukon 6 to 100 x 100mm spotter, which is easily supported on a good photo tripod, but this is an oddball.
For magnifications of 150x I suppose the 127mm Mak is best, but the 102mm f/5 should manage this also.

Regards, David
gooseholla
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Post by gooseholla »

Oh, how I wish, that in a large town wanting to be a city, that there was a telescope shop that I could go and check things out at!
David Frydman
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Post by David Frydman »

What about a local astronomy club or a star camp.

The Maksutov also has two mirror surfaces and they may reflect only 85% light each unless enhanced to say 95%.

So I don't think the light grasp of the 127 Maksutov is much more than a 102mm refractor.

However, the light lost to the secondary spectrum due to the f/5 false colour would mean that star images are more spread out than in the Mak.
So the Mak is probably better in light grasp and high magnification, say 150x to 180x than the refractor.

The refractor can get much wider fields especially if it takes 2 inch eyepieces.

There is actually too much choice nowadays.

David
gooseholla
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Post by gooseholla »

I agree that there is far too much choice. Four years ago, when I was looking for my first scope, I was advised to get a 3" refractor or a 6" reflector. I couldn't choose as there was so much out there for varying money. Fortunately, it was about the time Celestron C8 Newt. was being discontinued, so the choice was made for me.

Never had a 2 inch eyepiece. I get put off by people saying that a fast newt - whatever that is - won't take them as it will start to show the spider. Baffles me!

I don't know if there is a local one, well within a few minutes of here. I know there are some further out, but I don't have that much time to be driving places at night ( meant to be studying at Open U lol).

Thanks for your help.
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